The present invention relates to image processing methods, image processing apparatuses, and data storage media and, more particularly, to a coding process for superposing secret information on an image signal corresponding to each object and then coding the image signal. The invention also relates to a decoding process adapted to the coding process.
In recent years, we have greeted the age of multimedia in which audio, video, and other data are integrally handled, and the conventional information media, i.e., means for transmitting information to men, such as newspapers, magazines, televisions, radios, and telephones, have been adopted as the targets of multimedia. Generally, xe2x80x9cmultimediaxe2x80x9d means media in which, not only characters, but also diagrams, speeches, and especially images are simultaneously expressed in relation with each other. In order to handle the conventional information media as the targets of multimedia, it is necessary to express the information in digital formats.
When the quantity of data possessed by each of the above-described information media is estimated as the quantity of digital data, in the case of characters, the data quantity per character is only 1xcx9c2 byte. However, in the case of speech, the data quantity is 64 kbits per second (quality for telecommunication). Further, in the case of moving picture, the required data quantity is more than 100 Mbits per second (quality for current television broadcasting). So, in the above-described information media, it is not practical to handle such massive data as it is in the digital format. For example, although visual telephones have already been put to practical use by the ISDN (Integrated Services Digital Network) having a transmission rate of 64 kbpsxcx9c1.5 Mbps, it is impossible to transmit an image from a television camera as it is by the ISDN.
So, data compression techniques are demanded. For example, for visual telephones, the moving picture compression techniques based on the H.261 and H.263 standards which have been standardized by ITU-T (International Telecommunication Unionxe2x80x94Telecommunication Sector) are employed. Further, according to the data compression technique based on the MPEG1 standard, it is possible to record image data as well as audio data in an ordinary music CD (compact disk).
The MPEG (Moving Picture Experts Group) is an international standard of data compression for moving pictures, and the MPEG1 is the standard for compressing moving picture data to 1.5 Mbps, i.e., data of a television signal to about {fraction (1/100)}. Since the transmission rate of the targets to which the MPEG1 standard is directed is limited to about 1.5 Mbps, in the MPEG2 which has been standardized to meet the demand for higher image quality, moving picture data is compressed to 2xcx9c15 Mbps.
Furthermore, under the existing circumstances, standardization of MPEG4 is now proceeded by the working group for standardization of MPEG1 and MPEG2 (ISO/IEC JTC1/SC29/WG11), and this MPEG4 enables coding and signal processing in object units, and thereby realizes new functions required in the age of multimedia.
The MPEG4 has originally aimed at standardization of coding methods of low bit rates, but the target of standardization is now extended to more versatile coding methods of higher bit rates which are adaptable to an interlace image.
FIGS. 13(a)-13(d) are diagrams for explaining the object-by-object coding process.
FIG. 13(a) shows a composite image G corresponding to one frame in which three objects (i.e., fish, seaweed, and background) are composited.
In the object-by-object coding process, image signals corresponding to the respective objects constituting the composite image G, i.e., the background B (FIG. 13(b)), the fish F1 as a first foreground (FIG. 13(c)), and the seaweed F2 as a second foreground (FIG. 13(d)) are coded individually. Then, coded image signals corresponding to the respective objects are individually transmitted through a transmission medium or recorded in a recording medium.
On the other hand, in the object-by-object decoding process, the coded image signals corresponding to the respective objects are individually received through the transmission medium or reproduced from the recording medium. The coded image signals so obtained are decoded object by object to generate decoded image signals corresponding to the respective objects. Then, the decoded image signals corresponding to the respective objects are composited to obtain a decoded image signal corresponding to the composite image (decoded and reproduced image) G.
In the object-by-object coding process, together with the coded image signals obtained by coding the image signals corresponding to the respective objects, information (scene information) indicating the locations of the respective objects in one frame (display area of the composite image) for compositing the respective objects to be displayed is also transmitted through the transmission medium or recorded on the recording medium.
FIG. 14 is a diagram for specifically explaining information which is used as coding parameters in the object-by-object coding process.
In the object-by-object coding process, the following are coded for transmission or recording: pixel values (image signal) within an object area (hereinafter referred to as a rectangle area (BBOX)) including one object (e.g., the first foreground F1); size information (OBJsize) indicating the size (range) of the rectangle area; area position information (OBJpos) indicating the position of the rectangle area in an object coordinate system (individual coordinate system) corresponding to each object; and coordinate position information (FMpos) indicating the positional relationship between a composite image coordinate system (whole coordinate system) corresponding to a composite image and the object coordinate system corresponding to the object.
The object coordinate system (individual coordinate system) is a coordinate system used for coding of the image signal corresponding to the rectangle area, and it defines a display area corresponding to each object (VOP: Video Object Plane). Further, the composite image coordinate system (whole coordinate system) is a coordinate system used for composition of the respective objects, and it defines a display area (frame) F for displaying the whole composite image. Further, the size information (OBJsize) comprises the width and height of the rectangle area (BBOX). The area position information (OBJpos) is a position vector which indicates the direction and distance of a reference point or of the rectangle area (a point in the upper-left corner of the rectangle area) on the basis of an origin ob of the object coordinate system. The coordinate position information (FMpos) is a position vector which indicates the direction and distance of the origin Ob of the object coordinate system on the basis of an origin Og of the composite image coordinate system.
Since the area position information (OBJpos) is position information in the object coordinate system, it cannot be treated independently of the object-by-object coding process. However, since the coordinate position information (FMpos) is position information in the composite image coordinate system, it can be treated independently of the object-by-object coding process.
The purpose of representing the position of each object (i.e., the rectangle area) by using both of the area position information and the coordinate position information is to enable reuse and control of the object-by-object coded signals, in object units, without decoding the coded signals.
FIG. 15 is a block diagram for explaining the entire structure of a conventional image coding apparatus 200a. 
This image coding apparatus 200a encodes, object by object, image signals o1a, o1b, and o1c respectively corresponding to the background B, the first foreground F1, and the second foreground F2 which constitute the composite image G corresponding to one frame (display area of the composite image), and outputs the coded signals.
More specifically, the image coding apparatus 200a includes a first object encoder O1a which encodes the image signal o1acorresponding to the background B and outputs a coded object signal o3a; a second object encoder O1b which encodes the image signal o1b corresponding to the first foreground F1 and outputs a coded object signal o3b; and a third object encoder O1c which encodes the image signal o1c corresponding to the second foreground F2 and outputs a coded object signal o3c. Further, the image coding apparatus 200a includes a scene formation unit S1 and a scene encoder S2. The scene formation unit S1 generates coordinate position information (FMpos) s2 indicating the positional relationship of the object coordinate system to the composite image coordinate system, correspondingly to the scene information s1 relating to the locations of the respective objects in the composite image. The scene encoder S2 compresses the coordinate position information s2 by coding, and outputs the compressed information as a scene signal (coordinate position signal) s3.
Further, the image coding apparatus 200a includes a multiplexer T1 which multiplexes the scene signal s3 and the coded object signals o3a, o3b, and o3c corresponding to the respective objects, and outputs a multiplexed coded signal t1.
In the image coding apparatus 200a so constructed, when the image signals o1a, o1b, and o1c corresponding to the respective objects are input, these image signals o1axcx9co1c are subjected to coding of pixel values by the corresponding object encoders O1a, O1b, and O1c, respectively, whereby coded object signals o3a, o3b, and o3c corresponding to the respective objects are output from the respective object encoders to the multiplexer T1.
On the other hand, the scene information s1 relating to the locations of the respective objects in the image of one frame (composite image) is input to the scene formation unit S1. In the scene formation unit S1, the coordinate position information (FMpos) s2 indicating the positional relationship of the object coordinate system to the composite image coordinate system is generated in accordance with the scene information s1, and the coordinate position information (FMpos) s2 is output to the scene encoder S2. In the scene formation unit S2, the coordinate position information (FMpos) s2 is compressed by coding, and output as a scene signal s3 to the multiplexer T1.
In the multiplexer T1, the coded object signals o3axcx9co3c from the respective object encoders O1axcx9cO1c and the scene signal s3 from the scene encoder S2 are multiplexed to be output as a multiplexed coded signal t1.
FIG. 16 is a block diagram illustrating the structure of the conventional object encoder included in the image coding apparatus 200a. Since the respective object encoders O1axcx9cO1c in the image coding apparatus 200a are identical in structure, in the following description for FIG. 16, the object encoders O1axcx9cO1c are described as an object encoder O1, the image signals o1axcx9co1c are described as an image signal o1, and the coded object signals o3axcx9co3c are described as a coded object signal o3.
The object encoder O1 includes an area detector 11, an area extractor 12, and an image encoder 13. The area detector 11 detects the position of a rectangle area (BBOX) including an object in the object coordinate system and the size (range) of the rectangle area (BBOX), according to the image signal o1, and outputs area position information (OBJpos) 11a indicating the position of the rectangle area in the object coordinate system, and size information (OBJsize) 11b indicating the range (width and height) of the rectangle area. The area extractor 12 extracts the pixel values of pixels within the rectangle area (BBOX), i.e., the image signal corresponding to the rectangle area, with reference to the area position information 11a and the size information 11b. The image encoder 13 encodes the extracted pixel values to output a coded pixel value signal (coded image signal) 13a. 
Furthermore, the object encoder O1 includes a position encoder 14, a size encoder 15, and a multiplexer 16. The position encoder 14 encodes the area position information 11a to output an area position signal 14a. The size encoder 15 encodes the size information 11b to output a size signal 15a. The multiplexer 16 multiplexes the coded image signal 13a from the image encoder 13, the area position signal 14a from the position encoder 14, and the size signal 15a from the size encoder 15, and outputs the multiplexed signal as a coded object signal o3.
In the object encoder O1 so constructed, when the image signal o1 is input, the position and size of the rectangle area (BBOX) including an object in the object coordinate system are detected by the area detector 11, in accordance with the image signal o1, and the area position information (OBJpos) 11a and the size information (OBJsize) 11b are output from the area detector 11. Then, in the area extractor 12, the pixel values in the rectangle area (BBOX) are extracted with reference to the area position information 11a and the size information 11b, and the extracted pixels are encoded in the image encoder 13. At this time, the area position information 11a and the size information 11b are encoded in the position encoder 14 and the size encoder 15, respectively. Then, the outputs from the image encoder 13, the position encoder 14, and the size encoder 15 are multiplexed in the multiplexer 16 to be output as the coded object signal o3.
FIG. 17 is a block diagram for explaining the entire structure of a conventional image decoding apparatus 200b. 
This image decoding apparatus 200b decodes the multiplexed coded signal t1 which is output from the image coding apparatus 200a shown in FIG. 15, and generates a composite image signal c1 corresponding to the composite image.
More specifically, the image decoding apparatus 200b includes a demultiplexer T2 and object decoders O2a, O2b, and O2c. The demultiplexer T2 receives the multiplexed coded signal t1 from the image coding apparatus 200a, and separates the multiplexed coded signal t1 into coded object signal o7a, o7b, and o7c corresponding to the above-described coded object signals o3a, o3b, and o3c, respectively, and a scene signal s4 corresponding to the scene signal s3. The object decoders O2a, O2b, and O2c decode the coded object signals o7a, o7b, and o7c to output decoded object signals o9a, o9b, and o9c corresponding to the respective objects. These decoders also output area position information o8a, o8b, and o8c corresponding to the respective objects and equivalent to the above-described area position information (OBJpos) 11a. 
Further, the image decoding apparatus 200b includes a scene decoder S3, a display position formation unit S4, and a compositor C1. The scene decoder S3 decodes the scene signal s4 to output coordinate position information s5 equivalent to the above-described coordinate position information (FMpos) s2. The display position formation unit S4 calculates the positions of the rectangle areas corresponding to the respective objects in the composite image coordinate system for composition and display of the respective objects, from the area position information (OBJpos) o8axcx9co8c and the coordinate position information (FMpos) s5, and outputs display position information s6 indicating the display positions of the respective objects (rectangle areas). The compositor C1 composites the decoded object signals o9axcx9co9c in accordance with the display position information s6 for the respective objects, and outputs an image signal c1 corresponding to the composite image.
In the image decoding apparatus 200b so constructed, when the multiplexed coded signal t1 from the image coding apparatus 200a is input, the multiplexed coded signal t1 is separated into the coded object in o7axcx9co7c corresponding to the respective objects and the scene signal s4 in the demultiplexer T2. The demultiplexed coded object signals o7axcx9co7c are output to the corresponding object decoders O2axcx9cO2c while the scene signal s4 is output to the scene decoder S3.
In the object decoders O2axcx9cO2c, the corresponding coded object signals o7axcx9co7c are subjected to decoding of pixel values, thereby generating image signals o9axcx9co9c corresponding to the respective objects (decoded object signals) and area position information o8axcx9co8c corresponding to the above-described area position information (OBJpos) 11a. The image signals o9axcx9co9c are output to the compositor C1 while the area position information o8axcx9co8c are output to the display position formation unit S4.
On the other hand, the scene signal s4 is decoded in the scene decoder S3 to generate coordinate position information s5 corresponding to the above-described coordinate position information (FMpos), and this information s5 is output to the display position formation unit S4.
In the display position formation unit S4, the positions of the respective rectangle areas on the frames for composition and display of the respective objects are calculated from the area position information (OBJpos) o8axcx9co8c corresponding to the respective objects and the coordinate position information (FMpos) s5, and display position information s6 indicating the display positions of the respective rectangle areas on the frames is output to the compositor C1.
In the compositor C1, the decoded object signals o9axcx9co9c are composited according to the display position information s6, whereby an image signal c1 corresponding to the composite image is generated.
FIG. 18 is a block diagram for explaining the conventional object decoder included in the image decoding apparatus shown in FIG. 17. Since the respective object decoders O2axcx9cO2c in the image decoding apparatus are identical in structure, in the following description for FIG. 18, the object decoders O2axcx9cO2c are described as an object decoder O2, the coded object signals o7axcx9co7c are described as a coded object signal o7, and the decoded object signals o9axcx9co9c are described as a decoded object signal o9.
The object decoder O2 includes a demultiplexer 19, a position decoder 20, and a size decoder 21. The demultiplexer 19 demultiplexes the coded object signal o7 into a coded image signal corresponding to each object (rectangle area), a coded signal corresponding to the area position information (OBJpos) which indicates the position of the rectangle area in the object coordinate system, and a coded signal corresponding to the size information (OBJsize) which indicates the range of the rectangle area. The position decoder 20 decodes the coded signal 19b corresponding to the area position information to output area position information 200. The size decoder 21 decodes the coded signal 19c corresponding to the size information to output size information 201.
The object decoder O2 further includes an image decoder 22 which decodes the coded signal (coded image signal) corresponding to the pixel values of pixels in the rectangle area (BBOX) with reference to the area position information 200 and the size information 201, arid outputs a decoded object signal o9.
In the object decoder O2 so constructed, the input coded object signal o7 is demultiplexed into the coded signals corresponding to the pixel value information, the area position information (OBJpos), and the size information (OBjsize) in the demultiplexer 19. The coded signals corresponding to the area position information and the size information are decoded in the position decoder 20 and the size decoder 21 to be output as the area position information 200 and the size information 201, respectively. At this time, the area position information 200 is output as the area position information o8 to the outside. Further, in the image decoder 22, the coded image signal corresponding to the rectangle area (BBOX) is decoded with reference to the area position information 200 and the size information 201, and a decoded object signal o9 is output.
When the object encoder O1 shown in FIG. 16 is constructed so that the image encoder 13 performs inter-frame coding which uses pixel correlation between frames, the object encoder O1 can perform coding at a higher compression ratio. When the object encoder O1 is so constructed, the object decoder O2 shown in FIG. 18 is constructed so that the image decoder 22 performs inter-frame decoding, whereby the object decoder O2 can correctly decode the coded signal supplied from the object encoder O1 performing inter-frame coding.
Hereinafter, a description will be given of specific structures of an object encoder performing inter-frame coding and an object decoder performing inter-frame decoding.
FIG. 19 is a block diagram illustrating an object encoder O1a performing inter-frame coding.
The object encoder O1a shown in FIG. 19 includes an image decoder 32 and a memory 30 in addition to the constituents of the object encoder O1 shown in FIG. 18. The image decoder 32 decodes the coded signal 13a output from the image encoder 13, in accordance with the area position information 11a and the size information 11b from the area detector 11, with reference to an image signal 30a of a previous frame which has already been decoded. The memory 30 stores a decoded image signal 32a output from the image decoder 32. Further, in the object encoder O1a, the image encoder 13 performs inter-frame coding, that is, it encodes difference values between the pixel values from the area extractor 12 and the pixel values (image signal 30a) of the previous frame which have already been decoded and stored in the memory 30.
Since the position of the rectangle area BBOX corresponding to each object varies from frame to frame, the area position information 11a is input to the memory 30, whereby the memory 30 can read and write the already decoded image signal (reference image) in the object coordinate system.
FIG. 20 is a block diagram illustrating the structure of an object decoder O2a having an image decoder performing interframe decoding.
The object decoder O2a shown in FIG. 20 includes a memory 31 for storing a decoded image signal 22a output from the image decoder 22, in addition to the constructions of the object decoder O2 shown in FIG. 18. Further, in the object decoder O2a, the image decoder 22 decodes the coded image signal 19a output from the demultiplexer 19, in accordance with the area position information 200 and the size information 201, and adds the decoded image signal to the image information 31a of the previous frame which has already been decoded and stored in the memory 31, thereby restoring the image signal.
Further, in the object decoder O2a, as in the object encoder O1a shown in FIG. 19, the position information 200 is input to the memory 31, whereby the memory can read and write the already decoded image signal (reference image signal) in the object coordinate system.
The object decoder O2a so constructed can correctly decode the coded signal which is output from the object encoder O1a performing inter-frame coding.
By the way, the above-described method of coding an image signal in object units has the advantage that the image signal can be reused for each object independently. However, on the other hand, it has the risk that the image signal corresponding to each object is illegally reused.
So, in the case where the use of each object or the content as each object is that for which illegal use of the coded image signal corresponding to each object or reuse of the coded image signal in object units is to be inhibited, it is necessary to introduce means for deciding, when the image signal of each object is reused, as to whether the use of the image signal is legal or not (to be specific, embedding secret information such as copyright information relating to the object into the image signal corresponding to the object), or means for making reuse of the image in object units difficult.
As for the conventional object-by-object image coding method, no study has been conducted with respect to such illegal reuse of an image signal corresponding to each object, and it is the utmost to assume a method of embedding secrete information such as copyright information in the pixel values of the image signal, as a countermeasure against the illegal reuse. The method of embedding secrete information in the pixel values is a technique which has been developed for the conventional frame-by-frame coding method, and it may well be possible to apply this method to the object-by-object coding method by adding some technical modifications.
However, the method of embedding information in the pixel values is disadvantageous in that the embedding and extracting processes are complicated and, moreover, the image quality degrades because the pixel values are intentionally distorted.
The present invention is made to solve the above-described problems and has for its object to provide a method and an apparatus for image processing which can realize a coding process that makes it difficult to illegally reuse an image signal corresponding to each object, without degrading the image quality, by a relatively simple construction, and a method and an apparatus for image processing which can correctly decode a coded image signal obtained by the above-mentioned coding process, and furthermore, a data storage medium which contains a program for implementing the coding process and the decoding process by using a computer.
It is another object of the present invention to provide a method and an apparatus for image processing which can realize a coding process in which secrete information can be added to a coded image signal to be output, without degrading the image quality, and a method and an apparatus for image processing which can correctly decode the coded image signal obtained by the coding process, and furthermore, a data storage medium which contains a program for implementing the coding process and the decoding process by using a computer.
Other objects and advantages of the invention will become apparent from the detailed description that follows. The detailed description and specific embodiments described are provided only for illustration since various additions and modifications within the scope of the invention will be apparent to those of skill in the art from the detailed description.
According to a first aspect of the present invention, there is provided an image processing method for coding an image signal to display a predetermined composite image which comprises plural objects, the coding being performed for each of object areas which include the respective objects constituting the composite image. This method comprises the steps of: adding position disturbance information for disturbing the position of each object area, to area position information which indicates the position of the object area in an individual coordinate system for processing the image signal of the object area, thereby generating disturbed area information, and subjecting the image signal corresponding to the object area to a coding process based on the individual coordinate system, in accordance with the area position information or the disturbed area information, thereby generating a coded image signal corresponding to the object area; multiplexing a disturbed area signal obtained by coding the disturbed area information and the coded image signal corresponding to each object area, and outputting the multiplexed signal as a coded object signal for each object; adding the position disturbance information to coordinate position information which indicates the positional relationship between a whole coordinate system for displaying the whole composite image and the individual coordinate system corresponding to each object area, such that the position of each object area, which moves on the individual coordinate system in accordance with the position disturbance information, becomes unchangeable on the whole coordinate system in spite of the position disturbance information, thereby generating disturbed coordinate information; and multiplexing a disturbed coordinate signal obtained by coding the disturbed coordinate information arid the coded object signals corresponding to the respective objects to output a multiplexed coded signal. Therefore, even when the coded signal corresponding to each object is decoded, only the position of the object area disturbed by the position disturbance information is obtained, and the correct display position of the rectangle area in the whole coordinate system and the individual coordinate system cannot be obtained, thereby making illegal reuse of the image information of each object difficult. Further, since the position disturbance information is embedded, not in the pixel values corresponding to the rectangle area of each object, but in the area position information indicating the position of the rectangle area of each object, unwanted degradation of image quality of each object can be avoided.
According to a second aspect of the present invention, there is provided an image processing method for decoding the multiplexed coded signal obtained by the image processing method of the first aspect. This method comprises the steps of: separating the multiplexed coded signal into the disturbed coordinate signal and the coded object signals corresponding to the respective objects, and separating each of the coded object signals into the disturbed area signal and the coded image signal; decoding the disturbed area signal and the disturbed coordinate signal to generate the disturbed area information and the disturbed coordinate information, respectively; subjecting the coded image signal corresponding to each object area to a decoding process based on the individual coordinate system, in accordance with the disturbed area information, thereby generating a decoded image signal corresponding to each object area; and subjecting the decoded image signals corresponding to the respective object areas to a composition process based on the whole coordinate system, in accordance with the disturbed coordinate information and the disturbed area information corresponding to the respective object areas, thereby generating the image signal corresponding to the composite image comprising the respective objects. Therefore, the correct display position of the rectangle area of each object can be obtained in the whole coordinate in accordance with the coded object signal on which the position disturbance signal is superposed, whereby the image signal corresponding to the composite image can be correctly reproduced.
According to a third aspect of the present invention, in the image processing method of the first aspect, the position disturbance information is generated so that it includes specific information which is input from the outside, in accordance with the specific information. Therefore, the specific information can be embedded in the area position information corresponding to the object, whereby secret information or the like can be transmitted as the specific information, without degrading the image quality.
According to a fourth aspect of the present invention, there is provided an image processing method for decoding the multiplexed coded signal obtained by the image processing method of the third aspect. This method comprises the steps of: separating the multiplexed coded signal into the disturbed coordinate signal and the coded object signals corresponding to the respective objects, and separating each of the coded object signal into the disturbed area signal and the coded image signal; decoding the disturbed area signal and the disturbed coordinate signal to generate the disturbed area information and the disturbed coordinate information, respectively; subjecting the coded image signal corresponding to each object area to a decoding process based on the individual coordinate system, in accordance with the disturbed area information, thereby generating a decoded image signal corresponding to each object area; subjecting the decoded image signals corresponding to the respective object areas to a composition process based on the whole coordinate system, in accordance with the disturbed coordinate information and the disturbed area information corresponding to the respective object areas, thereby generating the image signal corresponding to the composite image comprising the respective objects; and extracting the specific information included in the position disturbance information, in accordance with the disturbed area information, and outputting the extracted specific information. Therefore, the correct display position of the rectangle area of each object can be obtained in the whole coordinate in accordance with the coded object signal on which the position disturbance signal is superposed, whereby the image signal corresponding to the composite image can be correctly reproduced. In addition, secret information or the like can be obtained from the coded object signal.
According to a fifth aspect of the present invention, there is provided an image processing method for coding an image signal to display a predetermined composite image which comprises plural objects, the coding being performed for each of object areas including the respective objects constituting the composite image. This method comprises the steps of: adding range enlargement information indicating the scale of enlargement for the range of each object area, to area range information which indicates the range of each object area in an individual coordinate system for processing the image signal corresponding to the object area, thereby generating enlarged area information; subjecting the image signal corresponding to the object area the range of which has been enlarged according to the scale of enlargement, to a coding process based on the individual coordinate system, in accordance with area position information indicating the position of the object area in the individual coordinate system, thereby generating a coded image signal corresponding to each object area; multiplexing an area position signal obtained by coding the area position information, an enlarged area signal obtained by coding the enlarged area information, and the coded image signal corresponding to each object area, and outputting the multiplexed signal as a coded object signal for each object; and multiplexing a coordinate position signal which is obtained by coding coordinate position information indicating the positional relationship between a whole coordinate system for displaying the whole composite image and the individual coordinate system corresponding to each object area, and the coded object signals corresponding to the respective objects, and outputting a multiplexed coded signal. Therefore, specific information can be embedded in the area range information corresponding to the object by superposing the specific information on the range enlargement information, whereby secret information or the like can be transmitted as the specific information without degrading the image quality.
According to a sixth aspect of the present invention, there is provided an image processing method for decoding the multiplexed coded signal obtained by the image processing method of the fifth aspect. This method comprises the steps of: separating the multiplexed coded signal into the coordinate position signal and the coded object signals corresponding to the respective objects, and separating each of the coded object signals into the area position signal, the enlarged area signal, and the coded image signal; decoding the coordinate position signal, the area position signal, and the enlarged area signal to generate the coordinate position information, the area position information, and the enlarged area information, respectively; subjecting the coded image signal corresponding to each object area to a decoding process based on the individual coordinate system, in accordance with the area position information and the enlarged area information, thereby generating a decoded image signal corresponding to each object area; subjecting the decoded image signals corresponding to the respective object areas to a composition process based on the whole coordinate system, in accordance with the coordinate position information and the area position information corresponding to the respective object areas, thereby generating the image signal corresponding to the composite image comprising the respective objects; and extracting the specific information embedded in the range enlargement information, in accordance with the enlarge area information, and outputting the extracted specific information. Therefore, secret information or the like can be obtained from the coded object signal.
According to a seventh aspect of the present invention, there is provided an image processing apparatus for coding an image signal to display a predetermined composite image which comprises plural objects, the coding being performed for each of object areas including the respective objects constituting the composite image. This apparatus comprises: a disturbance information generation unit for generating position disturbance information for disturbing the position of each object area in an individual coordinate system for processing the image signal of the object area; an area shifting unit for subjecting the image signal corresponding to each object area to an area shifting process by which the position of each object area in each individual coordinate system is shifted according to the position disturbance information, thereby generating an area-shifted image signal; an area detection unit for detecting disturbed area information which indicates the position or the object area in each individual coordinate system, in accordance with the area-shifted image signal corresponding to each object area; an image coding unit for subjecting the area shifted image signal corresponding to each object area to a coding process based on the individual coordinate system, in accordance with the disturbed area information, thereby generating a coded image signal corresponding to each object area; a multiplexer for multiplexing a disturbed area signal obtained by coding the disturbed area information and the coded image signal corresponding to each object area, and outputting the multiplexed signal as a coded object signal for each object; a coordinate information generation unit for adding the position disturbance information to coordinate position information which indicates the positional relationship between a whole coordinate system for displaying the whole composite image and the individual coordinate system corresponding to each object area, such that the position of each object area, which changes on the individual coordinate system in accordance with the position disturbance information, becomes unchangeable on the whole coordinate system in spite of the position disturbance information, thereby generating disturbed coordinate information; and a multiplexing unit for multiplexing a disturbed coordinate signal obtained by coding the disturbed coordinate information and the coded object signals corresponding to the respective objects, and outputting a multiplexed coded signal. Therefore, even when the area-sifted image signal is reproduced by a decoding process for each object, only the position of the object area disturbed by the position disturbance information is obtained, and the correct display position of the rectangle area in the whole coordinate system and the individual coordinate system cannot be obtained, thereby making illegal reuse of the image information of each object difficult. Further, since the image signal corresponding to each object area is subjected to the above-described area shifting process, unwanted degradation of image quality of each object can be avoided. Furthermore, it is possible to make illegal reuse of the image information of each object difficult by a relatively simple alteration of circuit, i.e., by adding only the disturbance information generation unit and the area shifting unit, thereby providing a coding apparatus of high practicality.
According to an eighth aspect of the present invention, there is provided an image processing apparatus for coding an image signal to display a predetermined composite image which comprises plural objects, the coding being performed for each of object areas including the respective objects constituting the composite image. This apparatus comprises: a disturbance information generation unit for generating position disturbance information for disturbing the position of each object area on an individual coordinate system for processing the image signal of each object area; an area detection unit for detecting area position information which indicates the position of each object area on each individual coordinate system, in accordance with the image signal corresponding to each object area; an area information processing unit for adding the position disturbance information to the area position information, thereby generating disturbed area information; an image coding unit for subjecting the image signal corresponding to each object area to a coding process based on the individual coordinate system, in accordance with the area position information, thereby generating a coded image signal corresponding to each object area; a multiplexer for multiplexing a disturbed area signal obtained by coding the disturbed area information and the coded image signal corresponding to each object area, and outputting a coded object signal for each object; a coordinate information processing unit for adding the position disturbance information to coordinate position information which indicates the positional relationship between a whole coordinate system for displaying the whole composite image and the individual coordinate system corresponding to each object area, such that the position of each object area, which changes on the individual coordinate system in accordance with the position disturbance information, becomes unchangeable on the whole coordinate system in spite of the position disturbance information, thereby generating disturbed coordinate information; and a multiplexing unit for multiplexing a disturbed coordinate signal obtained by coding the disturbed coordinate information and the coded object signals corresponding to the respective objects, and outputting a multiplexed coded signal. Therefore, even when the coded image signal corresponding to each object is decoded, only the position of the object area disturbed by the position disturbance information is obtained, and the correct display position of the rectangle area in the whole coordinate system and the individual coordinate system cannot be obtained, thereby making illegal reuse of the image information of each object difficult. Further, since the position disturbance information is added to the area position information indicating the position of the rectangle area of each object, unwanted degradation of image quality of each object can be avoided.
According to a ninth aspect of the present invention, there is provided an image processing apparatus for decoding the multiplexed coded signal output from the image processing apparatus according to the seventh or eighth aspect. This apparatus comprises: a demultiplexing unit for separating the multiplexed coded signal into the disturbed coordinate signal and the coded object signals corresponding to the respective objects; a demultiplexer for separating each of the coded object signals into the disturbed area signal and the coded image signal; an information decoding unit for decoding the disturbed area signal and the disturbed coordinate signal to generate the disturbed area information and the disturbed coordinate information, respectively; an image decoding unit for subjecting the coded image signal corresponding to each object area to a decoding process based on the individual coordinate system, in accordance with the disturbed area information, thereby generating a decoded image signal corresponding to each object area; and a composition unit for subjecting the decoded image signals corresponding to the respective object areas to a composition process based on the whole coordinate system, in accordance with the disturbed coordinate information and the disturbed area information corresponding to the respective object areas, thereby generating the image signal corresponding to the composite image comprising the respective objects. Therefore, the correct display position of the rectangle area of each object can be obtained in the whole coordinate system in accordance with the coded object signal on which the position disturbance information is superposed, whereby the image signal corresponding to the composite image can be correctly reproduced.
According to a tenth aspect of the present invention, in the image processing apparatus of the eighth aspect, the disturbance information generation unit generates the position disturbance information so that specific information supplied from the outside is included in the position disturbance information, in accordance with the specific information. Therefore, the specific information can be embedded in the area position information corresponding to the object, whereby secret information or the like can be transmitted as the specific information without degrading the image quality.
According to an eleventh aspect of the present invention, there is provided an image processing apparatus for decoding the multiplexed coded signal output from the image processing apparatus of the tenth aspect. This apparatus comprises: a demultiplexing unit for separating the multiplexed coded signal into the disturbed coordinate signal and the coded object signals corresponding to the respective objects; a demultiplexer for separating each of the coded object signals into the disturbed area signal and the coded image signal; an information decoding unit for decoding the disturbed area signal and the disturbed coordinate signal to generate the disturbed area information and the disturbed coordinate information, respectively; an image decoding unit for subjecting the coded image signal corresponding to each object area to a decoding process based on the individual coordinate system, in accordance with the disturbed area information, thereby generating a decoded image signal corresponding to each object area; a composition unit for subjecting the decoded image signals corresponding to the respective object areas to a composition process based on the whole coordinate system, in accordance with the disturbed coordinate information and the disturbed area information corresponding to the respective object areas, thereby generating an image signal corresponding to the composite image comprising the respective objects; and an information extraction unit for extracting the specific information embedded in the position disturbance information, in accordance with the disturbed area information, and outputting the extracted specific information. Therefore, the correct display position of the rectangle area of each object can the obtained in the whole coordinate system in accordance with the coded object signal on which the position disturbance information is superposed, whereby the image signal corresponding to the composite image can be correctly reproduced. In addition, secret information or the like can be obtained from the coded object signal.
According to a twelfth aspect of the present invention, there is provided an image processing apparatus for coding an image signal to display a predetermined composite image which comprises plural objects, the coding being performed for each of object areas including the respective objects constituting the composite image. This apparatus comprises: an area detection unit for detecting area position information which indicates the position of each object area on an individual coordinate system for processing the image signal of the object area, and area size information which indicates the range of the object area, in accordance with the image signal corresponding to each object area; an enlargement information generation unit for generating enlargement information for enlarging the range of the object area on each individual coordinate system; an information processing unit for converting the area size information to enlarged sized information which indicates the range obtained by enlarging the range of the object area by a scale according to the enlargement information; an image coding unit for subjecting the image signal corresponding to each object area to a coding process based on the individual coordinate system, in accordance with the area position information and the enlarged size information, thereby generating a coded image signal corresponding to each object area; a multiplexer for multiplexing an area position signal obtained by coding the area position information, an enlarged size signal obtained by coding the enlarged size information, and the coded image signal corresponding to each object area, thereby outputting a coded object signal for each object; and a multiplexing unit for multiplexing a coordinate position signal obtained by coding the coordinate position information which indicates the positional relationship between a whole coordinate system for displaying the whole composite image and the individual coordinate system corresponding to each object area, and the coded object signals corresponding to the respective objects, and outputting a multiplexed coded signal. Therefore, specific information can be embedded in the size information corresponding to each object by superposing the specific information on the enlargement information, whereby secret information or the like can be transmitted as the specific information without degrading the image quality.
According to a thirteenth aspect of the present invention, there is provided an image processing apparatus for decoding the multiplexed coded signal obtained by the image processing apparatus of the twelfth aspect. This apparatus comprises: a demultiplexing unit for separating the multiplexed coded signal into the coordinate position signal and the coded object signals corresponding to the respective objects; a demultiplexer for separating each of the coded object signals into the area position signal, the enlarged size signal, and the coded image signal; a decoding unit for decoding the area position signal, the enlarged size signal, and the coordinate position signal to generate the area position information, the enlarged size information, and the coordinate position information, respectively; an image decoding unit for subjecting the coded image signal corresponding to each object area to a decoding process based on the individual coordinate system, in accordance with the area position information and the enlarged size information, thereby generating a decoded image signal corresponding to each object area; a composition unit for subjecting the decoded image signals corresponding to the respective object areas to a composition process based on the whole coordinate system, in accordance with the coordinate position information and the area position information corresponding to the respective object areas, thereby generating the image signal corresponding to the composite image comprising the respective objects; and an information extraction unit for extracting the specific information embedded in the enlargement information, in accordance with the enlarged size information, and outputting the extracted specific information. Therefore, the coded object signal on which the enlargement information is superposed can be correctly decoded and, moreover, secret information or the like can be obtained from the coded object signal
According to a fourteenth aspect of the present invention, there is provided a data storage medium containing an image processing program, wherein the image processing program is a coding program for making a computer perform an image signal coding process according to the image processing method of the first or third aspect.
According to a fifteenth aspect of the present invention, there is provided a data storage medium containing an image processing program, wherein the image processing program is a decoding program for making a computer perform a coded image signal decoding process according to the image processing method of the second or fourth aspect.
According to a sixteenth aspect of the present invention, there is provided a data storage medium containing an image processing program, wherein the image processing program is a coding program for making a computer perform an image signal coding process according to the image processing method of the fifth aspect.
According to a seventeenth aspect of the present invention, there is provided a data storage medium containing an image processing program, wherein the image processing program is a decoding program for making a computer perform a coded image signal decoding process according to the image processing method of the sixth aspect.